1. Field of the Invention
The present invention is related to a memory cell, especially related to a memory cell having a read selection transistor and a program selection transistor.
2. Description of the Prior Art
Non-volatile memories (NVM) are capable of storing the information even when no power is supplied to the memory blocks. Due to the special characteristics, non-volatile memories are widely used in many kinds of applications. Programmable read-only memory (ROM) is a non-volatile memory commonly used by the field. In prior art, the programmable read-only memory includes rows of fuses, and the fuses can be burnt down by applying electricity to program the data to be stored. However, once the fuse is burnt down, it cannot be recovered. Therefore, after the programmable read-only memory is programmed the first time, it cannot be programmed again, and can only be read by other circuits.
Presently, the programmable read-only memory usually adopts anti-fuse capacitors to replace the fuses. By applying a high voltage to rupture the anti-fuse capacitor, the resistance of the anti-fuse capacitor would be altered and the data can be programmed. With the anti-fuse capacitor, the efficiency of the chip probe (CP) test and the final test (FT) can be improved, resulting in a higher yield rate of the programmable read-only memory. In addition, to control each memory cell of the programmable read-only memory, the programmable read-only memory has to be able to perform program operations and read operations to the desired memory cells. Therefore, to layout the memory cells efficiently while maintaining the flexibility of operations can be challenging.